The technical scope of the present invention is that of bases for ammunition intended to receive an electrical igniter.
Such bases are generally integral with an ammunition case and are intended to ensure gas-tightness with respect to the propellant gases upon firing.
When these bases are fitted with an electrical igniter the problem of the electrical contact between the igniter and the weapon system arises.
If such igniters generally incorporate an axial contact disc ensuring current lead-in, the reverse current generally occurs by means of the projectile in contact with the weapon""s ground.
Such a solution has numerous drawbacks.
First of all, the quality of the reverse electrical contact between the projectile and the weapon varies from one piece of ammunition to another and strongly depends on the surface smoothness of the weapon and the projectile as well as on any deposited impurities (namely any non-burned residue) they may carry.
Moreover, when the weapon""s ground is used as a reverse conductor the problem of electrical insulation arises. The weapon is live when a piece of ammunition is being ignited, which may deteriorate the equipment, namely the electronic equipment, integral with the weapon and notably risks harming the weapon crew.
This risk is all the greater and all the less acceptable in that the supply voltage of the igniter is high. Future weapon systems, however, will use high voltage electrical igniters in the form of one or several plasma torches or squibs. The voltages implemented will in this case be of around a few tens of kilo volts.
Such a reverse current via the weapon""s ground is thus complicated to achieve and the definition of an igniter having two current lead-in contacts at its rear causes problems of electrical insulation between these two contacts, which are too close to one another. There is the risk that the electric arc, in this case, will be produced at the contacts and not inside the igniter.
The aim of the present invention is to propose a base for ammunition that overcomes such drawbacks.
Thus, the invention relates to an ammunition base intended to receive an electrical igniter arranged in an axial bore, said base wherein it is made of a metallic material coated with an insulating material and in that it incorporates at least one non-insulated conductive area constituted by a ring-shaped bearing area of a shoulder of the base or by at least one non-insulated conductive ring crimped into a housing arranged in the base.
According to another characteristic of the invention, the axial bore incorporates female threading intended to ensure the attachment of the igniter, the female threading being free of insulating material and providing an electrical connection between the non-insulated conductive area and the igniter through the material of the base.
The insulating material may be a plastic or organic material.
The ring housing may be a circular groove made in a rear face of the base.
The housing may have a trapezoidal section profile.
The conductive ring may be made of copper or brass.
The conductive area, and namely the ring-shaped bearing area of a shoulder of the base, may have a metallic coating of copper or copper alloy.
The base according to the invention may advantageously carry an electric igniter comprising at least one plasma igniter.
Thus, the base according to the invention ensures a reliable electrical connection between an electrical igniter and a weapon system whilst providing an excellent level of electrical insulation. The contact resistance present at a base according to the invention is both low and reproducible from one base to another.